JPH08239336A - Production of perfluoroalkyl iodide telomer under catalysis of metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a desired middle chain perfluoroalkyl iodide telomer at a high conversion in high yield.

SOLUTION: This method is to produce perfluoroalkyl iodide telomer of the formula, Rf(CF₂-CF₂)_nI [Rf is a 1-6C perfluoroalkyl; (n) is a number of 1 to about 4; the maximum number of carbons in the obtained telomer mixture is 6-10] by reacting a perfluoroalkyl iodide of the formula, RfI (Rf is same as the before) with tetrafluoroethylene under copper as a catalyst, and uses further different transition metal as a cocatalyst.

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a perfluoroalkyl iodide telomer under the catalytic action of a metal.

[0002]

BACKGROUND OF THE INVENTION Medium- to long-chain perfluoroalkyl iodides are starting materials for the production of fluorinated surfactants and for the production of hydrophobizing and oleophobicizing agents, for example for textile materials. On the other hand, n-perfluorooctyl iodide is a starting material for n-perfluorooctyl bromide, which is very important especially in the medical field.

Perfluoroalkyl iodides have the following equation: RfI + nF ₂ C = CF ₂ → Rf (CF ₂ -CF ₂ ) _n I [wherein Rf has 1 to 6 carbon atoms. Alkyl and n is a number from 1 to about 8] according to the present invention. The reaction may be heated (eg US Pat. No. 5 268 516) or a free radical generator (eg GB 1 535).
408 or US Pat. No. 5,068,471). In the above thermal reaction, the dimerization of the intermediately occurring perfluoroalkyl radical yields a considerable amount of perfluoroalkane, while in the above free radical reaction a hydrogen-containing compound is produced as a by-product.

As shown by the above reaction equation, the formation of undesired long-chain telomers is generally suppressed by using a high concentration of telogen RfI. The desired selectivity for medium-chain telomers is therefore achieved at the expense of the effect of high conversion, which is a problem due to the very high cost of distilling the telogen to be recycled and the short chain telomers. The problem of occurring together remains.

"Preliminary Note" (Chen et al., Journal of
Fluorine Chemistry 36 (1987), 483 to 489),
The use of copper as a telomerization catalyst is described. This method has the advantage that the reaction already proceeds at 80-100 ° C. and requires a short reaction time compared to high temperature telomerization. But 1: 2 ~
In this reaction of 2: 1 molar ratio of perfluoroethyl iodide and tetrafluoroethylene, still relatively large amounts of undesired long-chain telomers are produced.

[0006]

Surprisingly, when copper is used in combination with yet another transition metal, the selectivity of copper as a catalyst in this telomerization reaction is increased towards the desired medium chain product. I knew I could do it. Therefore, the present invention provides that the formula Rf (CF ₂ -CF ₂ ) _n I [wherein Rf is a perfluoroalkyl having 1 to 6 carbon atoms and n is a number from 1 to about 4]. And the maximum number of carbon atoms in the resulting telomer mixture is 6-10.
The method of producing a perfluoroalkyl iodide telomer represented by the formula:
Has the meaning given above) with tetrafluoroethylene together with a catalyst consisting of copper and a further transition metal as cocatalyst.

The further transition metals mentioned above are metals which themselves do not catalyze the reaction or, if at all, only to a very weak extent, such as iron,
Cobalt, nickel, chromium, molybdenum, tungsten or titanium. Of course, one or more of these weakly active or inactive metals used can also be used in combination with copper. Even though the term "other" metal is used for brevity below, the present invention does not exclude the use of one or more weakly active or inert metals with copper. In addition, other catalytically active metals such as zinc, magnesium, vanadium, rhodium, rhenium or silver can also be used with copper.

Copper can be used in finely divided form as a mixture with other metals or as coatings for other metals. It can also be immobilized on a carrier with a large surface area. To this end, a conventional catalyst support,
Aluminum oxide, diatomaceous earth or molecular sieves are suitable, for example. If the reaction is carried out in an autoclave, the reaction zone can be made of or lined with one of the low-activity metals, such as steel or nickel, to give this material a thin copper coating.

The preferred telogens are 2-iodoperfluoropropane, and 1-iodoperfluoroethane, -butane and -hexane. It was found that the reaction rate using 1-iodoperfluorobutane and -hexane was about 1.6 times faster than that using 1-iodoperfluoroethane. Therefore, a preferred embodiment of the present invention consists in using these lower telomers as telogens in pure form or as a mixture.

Since the reaction according to the invention is a multiphase system, ie a system in which gaseous tetrafluoroethylene is reacted with liquid telogen on a solid catalyst, effective and vigorous mixing must be ensured. Therefore, supported catalysts in which the combination of metals is applied to a relatively low density support are advantageous. This is because by doing so, the floating property in the liquid perfluoroalkyl iodide phase is improved. Furthermore, it is advantageous to use a stirrer for introducing the tetrafluoroethylene into the liquid phase in gaseous form. Preference is also given to so-called jet reactors in which the liquid phase, together with the catalyst, is pumped in via a nozzle and circulated. The gas-in this case tetrafluoroethylene-is metered in just before the nozzle. The high shear forces generated at the nozzle result in effective gas / liquid transition. These reactors are also suitable for continuous processes.

It has also been found that the presence of water does not increase the formation of by-products when oxygen is scavenged, and furthermore that it hardly interferes with the reaction. Therefore, there is no need to dry the starting material.

[0012]

EXAMPLES The following examples further illustrate preferred embodiments of the present invention. The results were evaluated by gas chromatography and a direct evaluation of the data presented in parts by weight was obtained by an experimentally calibrated area coefficient.
Prior to use, the introduced perfluoroalkyl iodides were freed from impurities such as hydrogen fluoride or iodine with calcium carbonate powder and kept under a nitrogen atmosphere. The purity determined by gas chromatography is as follows: F ₂ C = CF ₂ 99.98% nC ₂ F ₅ I 97.5% nC ₄ F ₉ I 99.8% nC ₆ F ₁₃ I 98.7% iC ₃ F ₇ I 99.5 % Examples 1 to 12 Reaction was made of high-grade steel (V ₄ A, material 1.4571) 300
Performed in ml-shaking autoclave. First, the amount of catalyst shown in the table was introduced into an autoclave under a nitrogen atmosphere.
After a pressure test with 50 bar nitrogen, the autoclave was evacuated to 1 mbar and then cooled to -78 ° C. After inhaling the amount of perfluoroalkyl iodide shown in the table,
The desired amount of tetrafluoroethylene (referred to in the table as "TFE") was coagulated and introduced at -78 ° C (weighing must be done quickly to avoid errors caused by autoclave icing). Not). Examples 1 to 3 and Comparative Examples V1 and V2 69.2 g of 1-iodo-n-perfluorobutane, together with the amount of catalyst shown in the table and tetrafluoroethylene in the same molar ratio shown in the table for 5 hours at 100 ° C. Shaken. Table 1 shows the results. The sum of all non-RfI compounds is shown in the last column of the table as "Σ
X ". In a gas chromatographic evaluation, these compounds are weighed together using a weight factor of 1.00. These include, for example, tetrafluoroethylene, RfH compounds (which may be present in small amounts in the starting material). Included), perfluoroalkane and water, which are introduced into the system when the sample is dosed using a chilled syringe.

Nickel powder doped with 0.25 wt% copper was used in Examples 2 and 3. Unlike Example 2, in Example 3, tetrafluoroethylene was metered into the autoclave in two batches.

[0014]

[Table 1] Examples 4-11 The reaction was carried out analogously to the previous examples, but with the following catalysts. 34 mmol of nickel (II) acetate and copper (I
I) 3.4 mmol of acetate was dissolved in 150 ml of demineralized water.
The solution was concentrated to about 80 ml and stirred with the carrier materials listed in Table 2. This mixture is then added to 15mb
It was dehydrated at 190 ° C under a pressure of ar and activated by hydrogenating the catalyst at 250 ° C under 180 bar of hydrogen. During this operation, the pressure was released several times and hydrogen was reintroduced to remove acetic acid and residual water. The activated catalyst was kept under a nitrogen atmosphere. This is 7 g of nickel per gram
Contains 3.5% mg and 8.0 mg copper. 5 g of catalyst in each case
-That is 367.5 mg (5.78 mmol) copper and 40.0 mg nickel (0.68 m)
mol-) was used for each example. Also in each case 1-iodo-perfluorobutane 69.2 g (0.2 mol)
It was used. The results are shown in Table 2.

[0015]

[Table 2] Example 12 and Comparative Examples V3 and V4 Example 12 was performed in the same manner as Examples 1 to 3. In contrast, Comparative Examples V3 and V4 are perfluoroethyl iodide
Performed using 50 g. Table 3 shows the results.

[0016]

[Table 3] Example 13 and Comparative Example V4 19.5 Iodo-n-perfluorohexane 89.5 g was reacted at a temperature of 100 ° C. in a similar manner to the above-mentioned example. The results are shown in Table 4.

Comparative Example V2 shows the inertness of nickel (Table 1).

[0018]

[Table 4] Example 14 and Comparative Example V5 1200 g in Example 14 and 865 in Comparative Example V5
1-iodo-n-perfluorobutane (g) in a 1 L stirred tank with tetrafluoroethylene at a molar ratio of 2: 1 and 90 ° C
Each of them was reacted at the temperature of 2.5 hours for 2.5 hours. The stirring tank is equipped with a sheath for the thermocouple and a foaming stirrer, in which tetrafluoroethylene is introduced through a hollow stirring shaft and in the form of fine bubbles through fine holes at the ends of the stirring blades. Is introduced into the liquid phase in a spiral form. This foam stirrer has a maximum speed of 500 rpm. The results are shown in Table 5.

[0019]

[Table 5] Example 15 Perfluoroisopropyl iodide 29.6 g (0.1 mol)
5.0 g of tetrafluoroethylene (0.05 g) at a temperature of 100 ° C. in the presence of 1.0 g (17.0 mmol) of nickel and 0.05 g (0.8 mmol) of copper for 5 hours in the autoclave described in Examples 1-12. mmol). The results are shown in Table 6
Shown in

[0020]

[Table 6]

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location B01J 23/89 C07B 61/00 300 C07C 17/278 B01J 23/84 301X // C07B 61/00 300 311X

Claims (6)

[Claims] 1. A formula Rf (CF ₂ —CF ₂ ) _n I, wherein Rf is a perfluoroalkyl having 1 to 6 carbon atoms, and n is a number from 1 to about 4, The maximum number of carbon atoms in the resulting telomer mixture is 6 to
The perfluoroalkyl iodide telomer represented by the formula [10] is used as tetrafluoroethylene and a catalyst as a perfluoroalkyl iodide represented by the formula RfI (where Rf has the above meaning). A method of producing the same by reacting with the copper, further comprising using another transition metal as a cocatalyst. 2. The process of claim 1, wherein the metal used as cocatalyst is catalytically inactive by itself or has only a slight catalytic activity. 3. The method of claim 2 in which the metal, which by itself has little or no activity, is coated with copper. 4. The process of claim 1 wherein a catalytically active metal selected from the group consisting of zinc, magnesium, vanadium, rhodium, rhenium and silver is used as a cocatalyst. 5. The method according to claim 1, wherein the metal is fixed to a carrier.
Method 2 or 4. 6. The method according to claim 1, wherein tetrafluoroethylene is introduced into the liquid phase in a gaseous state by using a stirrer.